The National Cancer Institute, Division of Cancer Prevention and Control oversees an investigational agent development program for chemopreventive agents with potential for inhibiting the process of carcinogenesis. The purpose is to obtain new agents suitable for clinical trials in humans who do not have cancer but may be at increased risk for cancer. Agents being developed must be tested for toxicity in animals; all toxicologic data and a summary of toxicity observed in animals treated with the agent must be submitted to the FDA as part of an Investigational New Drug Application for human clinical trials. Thirteen Week Oral Toxicity Studies of Two Chemopreventive Agents To-Be- Named in Rats and Dogs: The protocols fulfill current industry standards for toxicology studies supporting IND applications and guidelines stated in the FDA Redbook. The protocols include observations of plasma drug levels, pharmacological & toxicological clinical observations, food consumption, weight gain, neurology, ophthalmology, cardiology, teratology, and clinical & anatomic pathology. The studies are conducted under: FDA GLP. Laboratories are AAALAC accredited, NIH/OPRR & USDA registered, and have active an IACUC.